One important focus area in E-UTRAN standardization work is to ensure that a new network is simple to deploy and cost efficient to operate. The vision is that new systems shall be self-organizing in as many aspects as possible.
Coverage and capacity (C&C) handling is attracting much interest in 3GPP Release 10, since it is seen as an OPEX driver. C&C is also a classical radio subject and can be said to cover a large area of problem definitions, solution activities, and tools.
In principle C&C is the problem of giving users coverage “inside” (e.g. a building), “behind” (e.g. a hill) and “far away”, while guaranteeing enough capacity so that the service level can be fulfilled.
As is evident in LTE and legacy systems as WCDMA and GSM, a radio network can be quite competent in configuring itself. The main reason is its possibility to measure via UEs. The network can for example change one parameter, say handover margin, and order UEs (and base stations) to measure the impact. Measurements like Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ) from UEs tell the system how the change had effect on UE and network performance.
Mobile telecommunication networks are gradually evolved; the network must handle increasing demands, with more nodes, more carriers and more users. The network must continuously be tuned to offer an acceptable quality. Traditionally this has been done via drive tests, to collect good enough information and planning tools to generate new settings for existing and new sites.
Today planning tools are the main method to generate a network plan and parameter settings. However a planning tool may suffer from inaccurate models which may imply non optimal planning proposals. Therefore one is bound to collect information from a real network. This may be done with dedicated UEs (drive tests) or normal UEs.
The benefit with drive tests is that they can be more accurate and directed to a specific geographical location (say a site's coverage area) while relying on normal UEs may suffer from a few samples and therefore takes time to generate the same accuracy. The benefit with normal UEs measuring is cost; it requires no personnel, no cars etc.
However, the biggest problem is that to be able to measure one must launch the plan, a plan that may have negative impact on users' quality experience. For example if relying on normal UEs in situations where a network reconfiguration would lead to UE loss, i.e. the UE will not have any coverage—the UE would be suffering from the coverage hole and even worse it would not be able to report loss of coverage back to the network.
Some solutions have been proposed to handle the above mentioned problem—3GPP now discusses possibilities for UEs to save logs and report back once they have coverage again, e.g. 3GPP TR 36.805 “Study on Minimization of drive-tests in Next Generation Networks”.